The power of an internal combustion engine is effected by the efficiency of the flow of exhaust gases through the exhaust port. An original factory port of an internal combustion engine is a basic approximation of the most desirable configuration for the flow of the exhaust gases. Frequently, engines are manufactured with exhaust port-passages that contain sharp bends and turns and abrupt changes in cross-sections that create stagnation areas. This results in decreased engine performance.
One approach to this problem has been to fill the stagnation areas by depositing metal in these stagnation areas through welding to reduce the actual cross-section area and improve the air flow. This method, however, is costly and cracking sometimes occurs in the weld area.
Another approach to this problem is disclosed in Cousimano U.S. Pat. No. 4,302,935. The Cousimano patent discloses a thick wedge-shaped insert of arcuate cross-section with upwardly curved margins that are installed by welding the insert onto a header plate engine prior to the securement of a header tube to the engine head. The header tube is then permanently welded to the header plate. Once the header plate and insert is welded to the header tube, it cannot be removed from the header tube.